Need help. Temp problems not sure why

2 things:

1. your carbon filter is not going to be as effective when you blow air through it. they perform much better sucking air in through them.
2. if you have a window in the room, couldn't you go down to lowes and buy their cheapo window ac? they make a frigidaire 5,000 btu that works really well and sells for $139 + tax

@Rednax Read your other thread. Especially the bit about measuring air temps correctly and the difference between a plants tolerance to radiant temps and air temps. You may not be in as bad of a position as you think!

And just to point out again. A black thermometer under direct light =

Even if you can control temps it won't matter much if you can't fresh air to the plants.

The exhaust from you grow box is depleted of co2 (plants used it). If that is just spit out into the room the grow box is in it will just be sucked back into the growbox, choking the plants out. You have to find a way to get that exhaust out of the room. OR you need to find a way to get loads of fresh air into the room so it can at least mix with the depleted exhaust air, before it is sucked back into the grow box.

If you don't the pics below will show you what happens. Notice the start on the pic with just the leaves. Then it gets progressively worse. And this was with some fresh air getting to the tent. just not enough.

Once the brown spots start you will come here asking why. People will tell you ph prob or salt build up. You will run around in circles flushing and all kinds of shit....when all you need to do is get fresh air to the plants.

Fresh air is one of the 3 most important things for you plant. Don't have one of those three and you don't have plants.

Hey everyone! Sorry I didn't post last night. Tore my hands up from using the wrong tool to move my intake down to the bottom. Also, been working on the box a lot lately till 4am then still getting up at 8-9am for fam time so was exhausted.

I do have a few updates. Two nights ago I worked on lowering my exhaust. That took me a while sadly so afterwards I did another temp test. After about an hour or so I checked in on her before going to bed and nothing changed. Still was sitting at 91 on the top and 89 on the bottom. This before I went to bed I adjusted the exhaust by putting it on the floor and running a line to the left side. After doing that and heading to bed the next day my bottom canopy stayed at 86 but my top was still 91. I feel as though this should be acceptable. Thank goodness finally. I think after closing my holes properly like Vemon said my top canopy should lower a bit too. Just didn't have time that night. This is what she looks like nowadays lol...


Tonight I am going to work on sealing up my holes in the back and adding my filer inside the box if I've got enough line. I also need to order my 2 gal smart pots and flex seal for the bottom so any draining doesn't rot my wooden floor. Ive thought about painting the inside white but I've got half a roll of Mylar left and no white paint on hand. I really don't think the Mylar is affecting the temp to be honest. Although I do need to re Mylar the inside. What you see now was left from the last grow attempt so that'll be gutted and redone soon.

After I get the holes filled in and filter on properly (thanks for the advise there) I am going to run a full 18 hour temp test to see if she holds. The box will be scheduled to be off for 6 hours (mostly for stealthily from the baby sitter) from noon to 6pm.

Everyone, please, cross your fingers for my full day temp test. I appreciate all the advise given and really couldn't have done this without you guys. Ignorance and bad design hurt me mostly so thanks again.

Seeds should be in Tuesday or Wednesday so I invite you all to join my journal if you have time. Not looking for big returns rather good experience, but it should be a perpetual 4-5 week harvest cycle so should be fun to watch!

coreywebster said:

@Rednax Read your other thread. Especially the bit about measuring air temps correctly and the difference between a plants tolerance to radiant temps and air temps. You may not be in as bad of a position as you think!

And just to point out again. A black thermometer under direct light =

Click to expand...

Just looked back at my older post. For some reason i wasn't getting alerts for that thread. Super thanks for the info. I'll address you there after I get some work done tonight.

Also there's a few other things/peeps I'd like to talk about but I need to get to work. Holler back later tonight or tomorrow.

Maybe this will help with setting up your box for better temp control.

Filter on the inside,exhaust fan outside the box ducted opposite & away from the inlet. Open and passive inlet (no fans). White thermostat. This setup will give you good exchange of air in your box and wont pull in any of the exhausted air keeping your grow box as cool as the room it is in. Plus less fans = less noise and less power consumption. The exhaust fan you have is major overkill for that size box so I'm sure a passive intake will work.

HydroRed said:

Maybe this will help with setting up your box for better temp control.
View attachment 3746574
Filter on the inside,exhaust fan outside the box ducted opposite & away from the inlet. Open and passive inlet (no fans). White thermostat. This setup will give you good exchange of air in your box and wont pull in any of the exhausted air keeping your grow box as cool as the room it is in. Plus less fans = less noise and less power consumption. The exhaust fan you have is major overkill for that size box so I'm sure a passive intake will work.

Click to expand...

Nice pic brother! That is exactly where I'm headed. Also, I appreciate you defining passive intake because I could not find a passive fan on eBay nor Amazon lol. Just car intakes and now I know why. However, my question would be without a fan on my intake (which I'm cool with) would my 170CFM fan suck in enough air? I know nothing about negative pressure either nor how to measure it. I've left it in so far for this temp test but I know a lot of people suggested it so I'd like to run a test without it too.

Furthermore, I did get some work done tonight. I'm about 90% done with light concealment. Found some mold that was left in there from one of my last attempts so sanded most of that out too. Need to pick a few things up at the hardware store tomorrow and that should wrap me up.

Edit= I did move my stats around so I hope they work better now. Let me know what you think @coreywebster Should have 5 total 3 white and 2 digital one black and one grey.

Here's what I got done tonight...

Gquebed said:

Even if you can control temps it won't matter much if you can't fresh air to the plants.

The exhaust from you grow box is depleted of co2 (plants used it). If that is just spit out into the room the grow box is in it will just be sucked back into the growbox, choking the plants out. You have to find a way to get that exhaust out of the room. OR you need to find a way to get loads of fresh air into the room so it can at least mix with the depleted exhaust air, before it is sucked back into the grow box.

If you don't the pics below will show you what happens. Notice the start on the pic with just the leaves. Then it gets progressively worse. And this was with some fresh air getting to the tent. just not enough.

Once the brown spots start you will come here asking why. People will tell you ph prob or salt build up. You will run around in circles flushing and all kinds of shit....when all you need to do is get fresh air to the plants.

Fresh air is one of the 3 most important things for you plant. Don't have one of those three and you don't have plants.

Click to expand...

I've started keeping the door open and the AC lower in the house. My exhaust is now pointed towards my door too. I've thought about buying a CO2 system but don't really want to spend more money until I've got the temps under control. Also, if I can get past August I might be able to vent out the window. Not sure how to correct this yet but I did see that in my last few attempts so I'll keep this in mind. Thanks for the info!

Co2 will do you no good in that box. You need a sealed room to run co2.

Damn thanks for the info though.

My opinion is to cut the proper size hole in top of box. Put it in so the exhaust ports and intakes are OUTSIDE of the box. That way minimal heat inside. Will work like a charm

Hows it going Rednax? Is 85 now your highest temp?

coreywebster said:

Hows it going Rednax? Is 85 now your highest temp?

Click to expand...

Sorry for the name change guys, couldn't remember this account's email, but I figured it out finally. Anyways, I did get the temps to what I believe is acceptable. Loving my latest set-up and really excited about getting some bean in the dirt. My temps are now running: Top canopy 8in from light with no direct light 90-92, mid canopy 14-16 in from light with direct light is running 88-85, bottom canopy 20 in from light no direct light 86-82, and side stats are registering 86-82 very consistently. Super excited I got her up and running. Thanks for the help everyone! Hope this thread helps another novice cab grower.

Here is a link to my Grow Journal if anyone is interested:
https://www.rollitup.org/t/600w-led-speed-bud-auto-cabgrow-first-sog-lo-oking-for-general-tips.916974/#post-12839001

Also, want to show everyone how fan I've came along so here is the front and back now: